A study was conducted to determine the growth rate of the reproductive organs of breeding female ostriches, which may be used in a prediction model for estimating nutrient requirements of breeders. Forty breeding female ostriches were sampled over an eight week period (five per week) starting at the onset of the breeding season. The ovary and oviducts were collected and weighed at each slaughter interval. No significant trend in the weight of the oviduct of the ostriches could be observed over the 49 d period, this weight being highly correlated with the body weight of the ostrich, whereas the ovary weight tended to be correlated with the time after the onset of the breeding period, although the variation in weights both within and between weights was very high. The variation in the weight of the ovary probably reflects differences in the laying pattern of individuals, and this lends itself to simulating the ovulatory cycle and consequently gaining a better understanding of the process, which would in turn aid in determining the requirement for the nutrients responsible for the growth of the ova.